Electron beam processing, such as electron beam welding of workpieces, typically takes place in a chamber, in which retaining tools for the workpieces are disposed. The workpieces are loaded onto and unloaded from the retaining tools through a closeable and sealable opening of the chamber. The processing takes place under a vacuum or reduced pressure, because the energy density of the electron beam is significantly reduced even at short distances under standard atmospheric conditions.
Relative movements between the electron beam and the workpieces are required for welding and are generated outside of the chamber, e.g., by beam deflection or by moving an electron beam generator relative to the workpiece. In the latter case, the electron beam generator is mounted, e.g., on a longitudinal- or X-Y carriage system, which is moved by a motor.
A chamber arrangement 10 of a known electron beam processing device having a carriage system is shown in FIGS. 4 and 5.
The chamber arrangement 10 includes a chamber housing 12. The chamber housing 12 defines a chamber interior space 14 having a circular cross-section perpendicular to a longitudinal axis 15 of the chamber housing 12 (see FIG. 5). Electron beam processing, such as e.g., electron beam welding of workpieces under vacuum or reduced pressure, takes place in the chamber housing 12. The chamber housing 12 has two mutually-opposing side walls 16, 18 (FIG. 5), an upper wall 20 having a planar upper side 21 extending in the horizontal direction in the view of FIG. 4, a lower wall 22 having a curved lower side 23, a planar rear wall 24 and a loading/unloading opening 26 disposed opposite of the rear wall 24. The side walls 16, 18 are connected with the rear wall 24, the upper wall 20 and the lower wall 22 in a pressure-tight manner. The upper wall 20 and the lower wall 22 mutually oppose each other and the rear wall 24 is disposed perpendicular to the upper wall 20 and the lower wall 22. The loading/unloading opening 26 is closeable in a sealed manner by a door 28. A (not-shown) seal is disposed around the edge of the loading/unloading opening 26, such that the seal is located between the edge of the loading/unloading opening 26 and the door 28 in the closed state.
A slot-shaped opening 30 is defined in the middle of the upper side 21 of the chamber housing 12. In this context, ‘slot-shaped’ is intended to encompass, but not be limited to, embodiments wherein the slot-shaped opening 30 is longer than it is wide, so that it has the shape of an elongated hole in a plan view. The slot-shaped opening 30 extends parallel to the longitudinal axis 15 of the chamber housing 12 and thus in a direction that extends perpendicular to the respective planes of the rear wall 24 and the loading/unloading opening 26.
As can be derived from the illustration of FIG. 4, the distance between the right-side edge of the slot-shaped opening 30 and the loading/unloading opening 26 is approximately 25% of the length of the slot-shaped opening 30. The distance between the left-side edge of the slot-shaped opening 30 and the rear wall 24 is less than 25% of the length of the slot-shaped opening 30. As a result, each of these distances is shorter than the length of the slot-shaped opening 30. A seal 31 is disposed on the upper side 21 so that it surrounds the edge of slot-shaped opening 30.
The chamber arrangement 10 further includes a carriage system 32. The carriage system 32 includes two supports 34, a carriage 36 and two linear guides 38. The supports 34 are rectangular box-shaped and have a length that corresponds to three-times the length of the slot-shaped opening 30. Consequently, in the mounted state, the supports 34 project in the direction of the longitudinal axis 15 considerably outwardly over the upper wall 20 and/or the upper side 21 beyond the rear wall 24 on one side and beyond the loading/unloading opening 26 on the opposite side. The supports 34 are disposed on the upper side 21 of the chamber housing 12 so that they mutually-oppose each other in a spaced, parallel relationship and they are parallel to the slot-shaped opening 30. The distance between each of the facing side surfaces of the supports 34 and the slot-shaped opening 30 is about twice the width of the slot-shaped opening 30. The linear guides 38 are formed as rails and have the same length as the supports 34. The linear guides 38 are disposed on the facing side surfaces of the supports 34.
The carriage 36 is disposed between the linear guides 38. The carriage 36 has a width that corresponds substantially to the spacing of the linear guides 38 and a length that is longer than twice the length of the slot-shaped opening 30. A round opening 40 is defined in the middle of the carriage 36. The round opening 40 has a diameter that is less than the width of the slot-shaped opening 30. The carriage 36 is disposed between the supports 34 so that it is linearly movable between and guided by the linear guides 38. The side of the carriage 36 that faces the chamber interior space 14 abuts on the seal 31. The opening 40 overlaps the slot-shaped opening 30 due to this spatial arrangement.
An electron beam generator 42 includes a beam nozzle 44 that is disposed on the lower side of the electron beam generator 42 and is fixedly connected with it. The electron beam generator 42 is disposed on the side of the carriage 36 that faces the chamber interior space 14 so that the beam nozzle 44 projects through the opening 40 and into the slot-shaped opening 30. Further, the electron beam generator 42 encloses the opening 40 in a pressure-tight manner. The electron beam generator 42 is adapted to generate an electron beam that propagates through the beam nozzle 44 along an electron beam axis 45 and into the chamber interior space 14.
During electron beam processing, a (not-shown) drive means moves the carriage 36 together with the electron beam generator 42 so that the electron beam can reach different positions within the chamber interior space 14. The geometric construction of the carriage 36 and the supports 34 enables the carriage 36 to abut on the seal 31 in every position and thus the chamber interior space 14 always remains sealed relative to the environment outside of the chamber arrangement 10 during an electron beam processing operation.